Patent Literature 1 discloses an embodiment of a heater device that forms a flat heat generating element. The flat heat generating element described in Patent Literature 1 is disposed to an interior member of a vehicle so as to surround the sides and upper parts of the feet of an occupant. In the heater device, the surface temperature of a side cover to which a side heater is disposed is controlled so as to be lower than the surface temperature of an upper heater to which an upper cover is disposed.